The present invention relates to a protective cap for medical HF instruments.
HF (high-frequency) instruments are commonly known, and are presented, for example, in the catalog of the company styled Karl Storz GmbH and Co., xe2x80x9cEndoskopische Chirurgiellxe2x80x9d [Endoscopic surgery], Section 6, 2nd ed. 1/94.
HF instruments are used for high-frequency coagulation or for high-frequency cutting.
High-frequency coagulation is used for surgical destruction of tissue areas, for hemostasis, to remove portions of tissue, or for thermal coagulation of tumors.
High-frequency cutting can be performed with HF instruments of the same design as for high-frequency coagulation high-frequency cutting is used, for example, to remove cysts, to cut through vessels, or for similar surgical interventions.
For use in the widely practiced technique of minimally invasive surgery, HF instruments are configured as tubular-shaft instruments.
Tubular-shaft instruments comprise a proximal handle and a shaft, joined immovably or detachably thereto, that is configured as a tubular shaft. Guided through this tubular shaft is a working insert that, at its distal end, projects beyond the shaft and carries the actual working device, for example a needle-shaped electrode or the mouth parts of a cutting or grasping tool.
The current to be applied is delivered via a high-frequency cable from a high-frequency generator arranged remotely from the HF instrument. For electrical connection to the instrument, a connector is provided on it. This connector usually comprises a metal pin mounted on the handle of the instrument and protruding from it.
The connector is in electrical contact with the actual working device, so that the current is guided through it to the distal end.
Whereas the connector for the high-frequency cable is generally immovably joined to the HF instrument, the generator is connected to the HF instrument, via the cable, only as necessary.
A distinction is made between unipolar and bipolar HF instruments, depending on the type of current delivery.
In a unipolar (also called monopolar) HF instrument, a connector for only one pole is provided on the instrument. The patient lies on an electrically conductive mat that constitutes the second pole. The current emerging from the distal end of the unipolar HF instrument flows over a large area through the patient""s body to the conductive mat.
In bipolar HF instruments, two connectors are present on the instrument, i.e. the current is fed in at the proximal end, delivered to a tool (e.g. a coagulation loop) at the distal end, then returned back to the proximal end and there discharged.
The term xe2x80x9cconnectorxe2x80x9d hereinafter comprises, in the case of mono- or unipolar HF instruments one connector, and in the case of bipolar HF instruments two connectors or connector plugs.
It has been found in practical use that electrical arcs can occur in the region of the connector plug, resulting in jerky reactions on the part of the surgeon. Adverse effects can also result from leakage currents.
A variety of solutions have hitherto been proposed for protecting the surgeon from such adverse effects.
For example the aforementioned catalog of Karl Storz GmbH and Co. shows, in Section 5 on page SCT 5/1 A, a handle for a tubular-shaft instrument having a connector for a unipolar high-frequency cable, in which insulation is achieved by the fact that the handle is made substantially of nonconductive plastic. Only the connector pin is made of metal, and is insert molded into the plastic. The handle has one fixed and one movable handle element, which can be moved relative to one another by way of a hinge joint made of plastic.
This type of insulation has the disadvantage that the handles do not exhibit sufficient mechanical stability.
The plastic hinge that was used could not withstand the mechanical stresses.
The pivot pins were therefore once again made of metal.
Since, however, the joints are located in close proximity to the connector for the high-frequency cable, the risk once again exists of voltage arcing or leakage currents from the connector to the metal hinge pin.
Because of the poor mechanical stability of plastic handle elements for HF instruments, it was alternatively proposed to utilize metal parts and to cover them with an electrically insulating plastic coating.
These coatings have not, however, proven durable over the long term. Handling, especially during cleaning and autoclaving, creates the risk that the coating can become damaged and can detach, and thereby expose metal areas of the instrument. In particular, a coating can exhibit less than complete coverage in areas where moving parts make contact with one another, for example at joints. This can result in arcs or leakage currents during HF use.
The purpose of the handle at the proximal end of the instrument, on which the connector for the high-frequency cable is present, is to control the distal end of the working device, e.g. spreadable mouth parts, extending through the tubular shaft.
For this purpose, an actuation element, usually in the form of a rod, projects proximally beyond the tubular shaft and is joined to a movable handle element of the handle. When the handles are, as is usual, scissor-like, one end of the handle element that is movable (i.e. pivotable) about the hinge axis is mechanically connected to the proximal end of the actuation element projecting beyond the tubular shaft, in order to convert a pivoting movement of the handle element into a linear displacement movement of the rod-shaped actuation element.
Ball-and-socket joints have proven successful as the mechanical connection, especially for instruments that can be disassembled. The usually solid, proximally projecting end of the metal actuation element is located, depending on the design, in the vicinity of the connector for the HF cable, and during HF operation also constitutes an exit point for arcs. Even insulation of this area cannot provide a remedy, since any insulation would soon be rubbed off by the frictional ball-and-socket mechanism.
With bipolar HF instruments, there exists the additional risk of arcing from the connector plug of the one pole to the connector plug of the other pole.
Against this background, it is the object of the present invention to create a reliable insulation system for HF instruments that does not adversely affect the stability and functionality of the other components of the HF instrument.
According to the present invention, the object is achieved by a protective cap which is configured such that it covers the instrument in insulating fashion at least in the vicinity of an electrical connector for a high-frequency cable.
This object is furthermore achieved by a medical HF instrument that has a protective cap of this kind.
The provision of an insulating protective cap eliminates the absolute necessity either for the HF instrument, or at least those regions of the HF instrument in which the connector for the high-frequency cable is located, to be produced entirely from insulating material; or, in the case of metallic materials, for them to be completely equipped with an insulating covering. For example, the handle including its joint and the connector for the high-frequency cable can be produced from metal, and nevertheless protected, in optimally electrically insulating fashion, against arcing once the protective cap has been attached. The protective cap thus makes it possible to manufacture those components that contain the electrical connector from mechanically stable and resistant material. Since the protective cap covers at least the vicinity of the electrical connector in insulating fashion, the danger of arcing or leakage currents to conductive elements and thus to the surgeon is eliminated. The electrical connector as such is, of course, electrically insulated with respect to the handles.
Depending on whether the instrument is configured as a unipolar or bipolar instrument, one connector plug or two connector plugs and their vicinity are covered in insulating fashion.
The protective cap can be manufactured as a relatively economical component from any material having good electrical insulation. When it is produced as a plastic injection-molded part, it can, for example, be designed for one-time use.
The HF instrument can thus be manufactured from suitable mechanically stable materials with no consideration of insulation against arcing in the region of the connector, since this is now accomplished by the protective cap that can be put in place subsequently or as required.
In a further embodiment of the invention, current-carrying components in the vicinity of the connector that are exposed, or that become exposed due to actuation of the HF instrument, are also covered by the protective cap.
This feature has the considerable advantage of ensuring, in all possible operating and handling positions, that not only exposed metal parts but also metal parts that become exposed during handling are covered. In the case of the aforementioned ball-and-socket joint connection between the actuation element in the tubular shaft and the handle element, a segment of greater or lesser length, depending on the pivot position of the handle element, is pulled proximally out of the shaft. Since the actuation element is at the same time utilized for electrical conduction to the distal end, it is necessarily manufactured from metallically conductive material and constitutes an exit point for arcs or leakage currents. The result is therefore to ensure that not only arcing from the electrical connector, but also adverse effects resulting from the proximally projecting metallically conductive actuation element, are eliminated.
In a further embodiment, the protective cap can be placed onto the HF instrument.
This feature has the advantage that the protective cap can be put in place only when needed, i.e. during HF operation, and otherwise the instrument can be used without the protective cap.
In a further embodiment of the invention, the protective cap can be placed onto a handle that has handle elements joined via a hinge joint, the protective cap extending over the hinge joint.
The advantage of this feature is that the hinge joint, regardless of whether the remaining handle elements are manufactured from plastic material or other materials, can comprise a metal pin, which contributes greatly to the mechanical stability of the handle and the joint. The protective cap proceeds from the connector and extends over the region of the joint, so that arcing to the metal joint pin is ruled out.
In a further embodiment of the invention, the shape of the protective cap is adapted to the contour of those parts of the HF instrument onto which it is placed.
The advantage of this feature is that the protective cap, once put in place, conforms closely to the contour of the HF instrument and does not constitute a bulky component that interferes with the surgeon. This rules out any need for the surgeon to grip the HF instrument differently, because the protective cap is in place, than in non-HF operation without the protective cap, thus enhancing handling ease and operating reliability.
In a further embodiment of the invention, the shape of the protective cap is configured such that movement of the handle elements in the region of the protective cap is possible without being limited thereby.
The advantage of this feature is that the protective cap covers the entire movement range of the handle elements, i.e. sufficient insulation is ensured in every handle element position, while at the same time the freedom of movement of the handle element is not limited despite the presence of the protective cap.
In a further embodiment of the invention, the protective cap can be slid onto a connector for a high-frequency cable that is joined immovably to the HF instrument and protrudes therefrom.
The advantage of this feature is that the cap can be slid over the connector onto the instrument in securely guided fashion. This procedure can be performed easily, quickly, and without close attention. A corresponding opening can be provided in the cap, through which the connector, protruding from the instrument, passes as it is slid on, so that the slid-on cap can then directly surround and cover the connector and therefore the principal source of the arcing hazard is insulated in particularly secure fashion.
In a further embodiment of the invention, the protective cap has a tubular extension that can be slid over a pin-shaped connector protruding from the HF instrument.
The advantage of this feature is that the cap, guided by the tubular extension, can be slid in directed fashion into a specific position on the HF instrument.
In a further embodiment of the invention, an attachment element is provided with which the protective cap can be secured on the HF instrument.
The advantage of this feature is that the protective cap is secured in particularly reliable and lossproof fashion, so that it cannot slip or become detached even if the HF instrument is set down between multiple treatment procedures.
In a further embodiment of the invention, the protective cap is made of an electrically insulating plastic material.
The advantage of this feature is that the protective cap can be manufactured from an economical material that can be manufactured, for example, using the injection-molding method, and thus can be designed as a disposable part for one-time use.
In a further embodiment of the invention, the protective cap is made of a ceramic material, e.g. an oxide ceramic or a glass ceramic.
The advantage of this feature is that a material that is not only insulating but also extremely mechanically strong is present, so that the protective cap can withstand even a large number of cleaning and autoclaving procedures.
In a further embodiment of the invention, the protective cap can be placed onto the HF instrument in detachable fashion.
The advantage of this feature is that the cap can be removed, either for cleaning or if the instrument is no longer being used in HF mode.
In a particular embodiment of the invention, the protective cap can be placed onto an HF instrument in which a handle is joined to a tubular shaft element via a releasable snap-lock connection, an actuation knob being present for closing and releasing the snap-lock connection, said knob being utilized to secure the protective cap.
The considerable advantage of this feature in this specific case is that attachment of the protective cap can be simultaneously accomplished using a component already present on the HF instrument. For the cleaning process, the instrument can be disassembled in such a way that the protective cap is present as an individual part, and can be cleaned correspondingly.
In a further embodiment of the invention, the protective cap itself has a connector for a high-frequency cable, and after placement onto an HF instrument, the connector is connected to a conductive part of the HF instrument.
This feature has the advantage that the connector, which is usually configured as a metal connector pin, is integrated into the protective cap, so that provision is already made during manufacture for a correspondingly insulated connection between these two components. Once the protective cap is put in place, the connector integrated into it creates the electrical connection between the HF connector cable and the conductive component of the HF instrument. In the case of a bipolar HF instrument, two connector plug pins are present.
In a further embodiment of the invention, provision is made for handling features, which facilitate placement or removal of the protective cap, to be present on the protective cap.
The advantage of this feature is that a replacement operation can be performed easily and reliably.
In a further embodiment of the invention, the handling features comprise grip elements, grip ribs, a shaped-on handle, or a roughening.
These features on the one hand are very easy to carry out in terms of production engineering, especially in the case of a configuration as an injection-molded part; and on the other hand they constitute unequivocal handling features for the fingers of a human hand, so that secure grasping and removal or placement are possible even without close attention, and in particular without direct visual contact.
In a further embodiment of the invention, the protective cap can be mounted onto the HF instrument and pulled off from it only when the grip elements are in a specific position.
The advantage of this feature is that the grip elements constitute a specific securing means for the protective cap with no necessity for an additional operating element for the purpose.
In a further embodiment of the invention, the protective cap is joined to the high-frequency cable.
The advantage of this feature is that the protective cap becomes part of the plug connector.
It is understood that the features mentioned above and those yet to be explained below can be used not only in the respective combination indicated, but also in other combinations or in isolation, without leaving the context of the present invention.